1. Field of the Invention
The invention relates to a device for communicating with a portable data medium in a communication using at least a power signal supplied by an electric energy source, a control signal and a data transmission signal.
2. Description of Related Art
Typically, the portable data medium can be a chip card incorporating a microprocessor or microwired logic circuits defining areas to which access is controlled and thus capable of containing secret information such as cryptographic keys (see for example the portable object described in U.S. Pat. No. 4,211,919).
The object of the invention is to offer an original solution for solving the general problem of the sequencing of the signals, particularly so as to comply with the standards applicable in this case (for example ISO standard 7816-3). It makes it possible, in a simple way, to meet the contradictory requirements of detecting the interruption of the power signal if the portable data medium is removed, and of continuing to supply this signal to the portable data medium for a given time after this detection.